The top-of-the-line card will be known as the Radeon X2800XTX2 and will be the same concept as Nvidia's GX2 card. So you can expect two R600 chips on a card. We don't know how DAAMIT plans to implement this, as we may be talking about two PCBs or maybe just one. Nvidia went for two PCBs last year with its Geforce 7950GX2 and our money is on ATI following a similar route.
We also have the rest of the specs, although final clocks may still change slightly. Both chips should end up clocked at 575MHz core and 2000MHz GDDR4 memory. This version has the 256-bit memory controller probably because of technical difficulties to make two chips work at 512-bit memory controller speed. The card is equipped with 2x512MB memory, a total of 1GB, and has two times 96-Shader units. It is made using a 80 nanometre process.
The best of all is that it will cost $600. This was ATI's best-kept secret so far but Nvidia is also doing some dual G80 card to compete this one.
The single R600 called Radeon X2800XTX will be clocked at higher speeds with better specs. Stay tuned. Oh yes, this is how Quad Crossfire is actually going to work. Just plug two of these cards. You can read more about that here. ยต